Checkout with the -p switch uses the "add interactive" framework which
is written in Perl.
One test added in 8d7b558bae ("checkout & worktree: introduce
checkout.defaultRemote", 2018-06-05) didn't declare the PERL
prerequisite, breaking the test when built with NO_PERL.
Reported-by: CB Bailey <cb@hashpling.org> Signed-off-by: CB Bailey <cb@hashpling.org> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>